The invention relates to a disposable hygiene article or surgical covering item, or surgical garment for single use, such as an incontinence diaper, incontinence pad, surgical drape, or surgical coat, comprising a composite nonwoven fabric, that is provided with at least one nonwoven fabric component and another nonwoven fabric or film component. The first nonwoven fabric component is attached to the other nonwoven fabric or film component in at least some areas by means of a joining pattern encompassing discrete ultrasonic welding points in order to form the composite nonwoven fabric. The joining pattern extends in a longitudinal direction and a transverse direction that runs perpendicular thereto, the distance in the longitudinal direction being longer than the distance in the transverse direction. At least some sections of the joining pattern are curved.
For example, on hygiene articles, in particular, incontinence products, such as incontinence diapers, lateral barriers standing toward the user during use, called cuff elements, are provided that comprise a nonwoven fabric component and are attached in the longitudinal direction of the product to another nonwoven fabric or film component of the hygiene article by means of ultrasonic welding or bonding. In the field of the hygiene articles addressed here, the joining of nonwoven fabric and/or film components by means of ultrasonic welding devices is generally known. For example, a joining pattern comprising discrete ultrasonic welding points can be implemented in a continuous, that is, never-ending production machine for nonwoven articles of the type stated above by using a contour roller rolling in the machine direction and an anvil made to vibrate in the ultrasonic range, which is termed a sonotrode. The contour roller and sonotrode form a gap between them through which the weldable components to be joined are fed during the continuous production process. The nonwoven fabric or film components are then welded by transfer of the vibration energy on the raised areas of the contour roller. The strength of the weld can be adjusted by varying the distance between the sonotrode and the contour roller and by controlling the vibration of the sonotrode.
The applicant has ascertained that, in particular, on fast-operating production machines, it is extremely difficult to achieve a uniformly secure weld without damaging the components if the area of the weld varies greatly in the machine direction, because this necessitates very frequent variation in control of the welding device or its sonotrode. It is extremely difficult to almost impossible to achieve a stable operating condition. If, on the other hand, the area of a joining pattern varies little or not at all in the machine direction, for example, if it does not vary in the circumferential direction of the contour roller and, for example, comprises concentric embossing lines or embossing points on the contour roller, the problem described above does not occur because the welded area does not change so rapidly in the machine direction. If, on the other hand, the joining pattern is oblique with respect to the machine direction or comprises oblique sections, the proportion of the welded area in the machine direction will vary greatly and the problems described above will occur. If, for example, on one product, the joining pattern comprises arc-shaped areas with tight curvature with respect to the machine direction, achieving process reliability in the welding of nonwoven fabric components poses a problem. If this problem is not solved, unwelded points or damage to the nonwoven fabric or film components due to overwelding will occur. In either case, correct functioning of the article being produced is jeopardized. Extremely short control cycles in operating the ultrasonic welding device can also result in the device overshooting and frequently causing direct contact between the contour roller and the sonotrode. This results in damage to the device, considerably reducing its service life. The sonotrode and contour roller then require frequent replacement due to the high wear caused by direct contact between the two machine components.
The object of this invention is to provide a hygiene article or a surgical covering item or surgical garment of the type described above with which the problems described above do not occur, while nevertheless permitting production of a joining pattern of discrete ultrasonic welding points that varies in the machine direction. For example, it must be possible to fix a standing cuff element according to a joining pattern that oscillates in the form of arcs with respect to the machine direction or generally to join weldable nonwoven fabric or film components of the article stated above fed in as flat material without being limited to a joint that is precisely straight in the machine direction. In particular, damage to components being welded together during the welding process and partially deficient welding of the components must be precluded. Similarly, damage to the ultrasonic welding device must be avoided and a long service life ensured in conjunction with fast-operating production machines.